By using a combination of drugs, electrical stimulation, and robot-assisted rehabilitation, researchers have restored a remarkable degree of voluntary movement in rats paralyzed by a spinal cord injury. After several weeks of therapy, the rodents were able to walk with assistance, to recover a piece of food, even climbing stairs or climbing a small fence to get it. Rats recovery raises hopes that a similar combination strategy may help restore movement in some people with lesions of the spine. Indeed, these efforts are already underway.
Spinal injuries cause paralysis because they break or crush the nerve fibers that connect the brain to the spinal cord neurons that move muscles throughout the body. These fibers or axons, are the long extensions that carry signals from one end of a neuron to another, and unfortunately, they do not regenerate in the adult. That's why the paralysis of an injury to the spine is a lifelong disability. Restore the ability of axons to grow back using growth factors, stem cells, or other therapies was long-elusive goal, but frustrating for researchers.
The new study, which appears in Science today, takes a different approach. Instead of trying to repair the main information highway brain to the body, Grégoire Courtine, of the Swiss Federal Institute of Technology Lausanne, and colleagues focused on alternative routes. Most injuries of the spine in people who do not cut the spinal cord completely, explains Courtine. To approach this in rats, her team made two surgical cuts in the spinal cord, cut all direct connections of the brain, but leaving some intact tissue between cuts. Then they had rodents begin a rehabilitation scheme to circumvent the highway fractured, so to speak, by pushing more traffic on neural back roads and the construction of several of them.
The scheme, which began about a week after the rats were injured, lasted about 30 minutes a day. During each session, researchers injected animals with a cocktail of drugs to improve the function of neural circuits of rats in the portion of the spinal cord involved in the movements of the legs, and they have stimulated this area with electrodes. With his spinal cord and primed for action, a rat was installed in a harness attached to a robotic device that supported his weight and allowed him to walk forward on its hind legs to the extent that it could. Initially, the rats could not move his legs at all, let alone walk.
But after 2 or 3 weeks, the rodents began to take steps for a piece of food after a little push from the robot. In 5 or 6 weeks, they were able to initiate movement of their own and walk to get food. And after a few more weeks of intensified rehabilitation, they managed to climb the stairs and size rat up on a small barrier placed in their way. The rats that do not undergo rehabilitation, however, showed no improvement. Rats suspended over a treadmill in movement that sparked a reflex movement as progress, has not improved either, suggesting that complete recovery depends on making voluntary movements, not just any movement.
"It is a truly remarkable finding," said Michael Beattie, a neuroscientist at the Brain and Spinal Injury Center at the University of California, San Francisco. Additional experiments in the document are convincingly that the recovery of rats is due to new neural connections forming to create a detour around the wound, he said. Beattie noted that the work of Courtine suggests that the three components of the strategy-Rehab drugs, electrical stimulation, and physical robot-assisted therapy appear to be necessary to maximize recovery. "I think it gives a lot of hope that this kind of strategy will have a great reward" in people, Beattie said.
a study last year published the case reported some recovery of voluntary movement in a man paralyzed in a car accident after suffering a combination of electrical stimulation and physical therapy. The new research rodents provides a possible explanation for the recovery of this patient, said one of the main authors of the case study, neuroscientist V. Reggie Edgerton at the University of California, Los Angeles. Edgerton said two other patients are being similar rehabilitation now, and his group hopes to add medication to improve nerve repair in the future. "We do not yet have there," he said. "But the bottom line is, things are still looking good."
By encouraging new results, Courtine is careful to note the limits of the strategy. on the one hand, it would not work if the spinal cord has been completely severed. in addition, the treated rats could make voluntary movements while electrical stimulation was turned on, and the same was mostly real patient Edgerton and colleagues worked with. "This is not a cure for spinal cord," explains Courtine. "It is a promising proof of principle."
0 Komentar